Usury (lending with interest) isn't the best example since the interest is more than an economic rent - as you say, it is a consideration for the risk, and credit funding is critical for regular business operations in our economy.

However, there are many forms of true economic rents, which do constitute money earned for no (productive) work. To name a few, there are monopoly rents, copyright and patent trolling, corruption (e.g. bribes, lobbying), inappropriate subsidies, etc.

Going to back to banks and lending, harmful rents are extracted by bank officers who engage in looting, the practice of knowingly making bad, high-interest loans to meet short term profit goals while ultimately ensuring losses because of the inevitable defaults. This practice is unfortunately commonplace in the modern banking sector and has played a major role in multiple financial crises.